Raman excitation profiles of conjugated segments in solution

Heller, C.; Leising, G.; Godon, C.; Lefrant, S.; Fischer, Wolfgang; Stelzer, Franz

doi:10.1103/physrevb.51.8107

Cited by 42 publications

(29 citation statements)

References 30 publications

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“…Within a certain range, the 1 and 2 vibrational bands of the polyene molecules depend linearly on the inverse of the molecular chain length (1/n) 30,32,36 or its logarithms. 2 Plotting 1 vs 2 thus yields a linear trend of both increasing 1 with 2 , at decreasing number of double bonds.…”

Section: Discussionmentioning

confidence: 99%

“…Bands obtained by excitation with different wavelengths that appeared within š2 cm 1 were taken as the identical peak, as these are most likely caused by the Raman shift at different laser wavelengths. 30,32,36 Tables 1 and 2 give the central positions of the pigment signals ( 1 , 2 ) and decomposed components 1 , 2 i , as well as their FWHMs and calculated maximum number of conjugated double bonds or 'effective conjugation lengths' (N eff ). 2…”

Section: Methodsmentioning

confidence: 99%

“…During excitation with lasers of different energies, not only the shape of the Raman spectrum changes, but also the scattering intensity 30 and a single component of a polyene mixture can be enhanced or suppressed to resolve the mixture. 30,32,36 Pigments related to bio-aragonite were identified as mixtures of unmethylated polyenes. 2,3,5,6,11 Using the differentwavelength-enhancement method, at least four and up to nine pigments were reported in the same pearl, even in homogeneously pigmented zones, whereas different colours were explained by mixtures of polyenes with different chain length.…”

Section: Pigments In Biominerals By Raman Spectroscopymentioning

confidence: 99%

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Micro‐Raman spectroscopy of pigments contained in different calcium carbonate polymorphs from freshwater cultured pearls

Soldati

Jacob

Wehrmeister

et al. 2008

J Raman Spectroscopy

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The metastable calcium carbonate polymorph vaterite has recently been found to occur commonly in freshwater cultured pearls from Japan and China. Organic pigment molecules in these vaterite regions of freshwater cultured pearls were analysed by resonance and near-resonance micro-Raman spectroscopy, in single spectra and in mapping modes and are compared with their aragonitic counterparts. Four different excitation wavelengths (487.9, 514.5, 532.2 and 632.8 nm) were used, resulting in differential increase of resolution for the pigments. Although vaterite areas were always lightly coloured (light yellow, light brown or white), ten different pigments were identified and a single colour is formed by a combination of three and up to nine polyenes of different lengths. The molecules were identified as unmethylated polyenes with effective chain lengths between 8 and 12 conjugated double bonds and FWHMs of 10 ± 2 cm −1 . Additionally, and for the first time in pearls, methylated polyenes were detected together with unmethylated pigments in aragonite. Polyenes with chain lengths shorter than 8 or longer than 12 were not found in vaterite, whereas both shorter and longer pigment chains were observed in aragonite from the same pearls. Pigments have lower concentrations in vaterite and are distributed more homogeneously, while they have higher concentrations in aragonite and are arranged along the annual growth lines of the pearls.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Pigments In Biominerals By Raman Spectroscopymentioning

confidence: 99%

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Micro‐Raman spectroscopy of pigments contained in different calcium carbonate polymorphs from freshwater cultured pearls

Soldati

Jacob

Wehrmeister

et al. 2008

J Raman Spectroscopy

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“…47,48 The rationale for the apparent shifting of polymer backbone bands with excitation wavelength is that the polymer is made up of domains with differing effective conjugation lengths, which come into resonance at differing excitation frequencies and possess slightly different backbone vibrational frequencies. 37 We have examined the resonance Raman spectra of oxidized poly-3e and find that there is a frequency dispersion effect on the line B polythiophene band ( Figure 5).…”

Section: Methodsmentioning

confidence: 99%

Indanedione-Substituted Poly(terthiophene)s: Processable Conducting Polymers with Intramolecular Charge Transfer Interactions

et al. 2010

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Officer, D. L. (2010). Indanedione-substituted poly(terthiophene)s: Processable conducting polymers with intramolecular charge transfer interactions. Macromolecules, 43 (8), 3817-3827. Indanedione-substituted poly(terthiophene)s: Processable conducting polymers with intramolecular charge transfer interactions AbstractThe electrochemical and chemical syntheses of poly(terthiophene)s bearing an indanedione pendant group and displaying intramolecular charge transfer interactions have been achieved. The nature of the charge transfer interaction is characterized through DFT calculations and experimental studies, including resonance Raman spectroscopy and absorption and emission data through a Lippert-Mataga analysis. It is found that the low-energy transition present in the indanedione-bearing monomer species has considerable charge transfer character with a dipole change of II D. Decomposition of the indanedione group occurred during hydrazine reduction after chemical polymerization. A soluble, low molecular weight indanedione-substituted polymer (weight average 4500 Da) was nonetheless obtained following the use of a milder reducing agent, triethanolamine. To the best of our knowledge, this is the first example of the use of triethanolamine for the reduction of an oxidized polythiophene, providing a milder and safer alternative to hydrazine. In an attempt to produce higher molecular weight processable polymers with intramolecular charge transfer interactions, a copolymer of the indanedione-substituted terthiophene and a dihexylterthiophene was synthesized. The electronic conjugation of the produced polymers was characterized by Raman frequency dispersion experiments and show dispersion rate parameters similar to those observed for other substituted polythiophenes. ABSTRACT: The electrochemical and chemical syntheses of poly(terthiophene)s bearing an indanedione pendant group and displaying intramolecular charge transfer interactions have been achieved. The nature of the charge transfer interaction is characterized through DFT calculations and experimental studies, including resonance Raman spectroscopy and absorption and emission data through a Lippert-Mataga analysis. It is found that the low-energy transition present in the indanedione-bearing monomer species has considerable charge transfer character with a dipole change of 11 D. Decomposition of the indanedione group occurred during hydrazine reduction after chemical polymerization. A soluble, low molecular weight indanedionesubstituted polymer (weight average 4500 Da) was nonetheless obtained following the use of a milder reducing agent, triethanolamine. To the best of our knowledge, this is the first example of the use of triethanolamine for the reduction of an oxidized polythiophene, providing a milder and safer alternative to hydrazine. In an attempt to produce higher molecular weight processable polymers with intramolecular charge transfer interactions, a copolymer of the indanedione-substituted terthiophene and a dihexylterthiophene was synthesized. The ...

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“…The peaks at 1656 and 1443 cm ±1 , representing carbon±carbon double bonds (C=C), are in agreement with the two corresponding stretching peaks found in the known spectra of poly(norbornene) compounds. [53] The peak at 1294 cm ±1 in Figure 5C suggests that the C=C bond in the poly-5 has a trans geometry. The absence of the cis-CH symmetric vibration mode in Figure 5C confirms the polymerization of 5.…”

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confidence: 99%

Solventless Polymerization at the Gas–Solid Interface to Form Polymeric Thin Films

Weng

et al. 2002

Adv. Mater.

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Raman excitation profiles of conjugated segments in solution

Cited by 42 publications

References 30 publications

Micro‐Raman spectroscopy of pigments contained in different calcium carbonate polymorphs from freshwater cultured pearls

Micro‐Raman spectroscopy of pigments contained in different calcium carbonate polymorphs from freshwater cultured pearls

Indanedione-Substituted Poly(terthiophene)s: Processable Conducting Polymers with Intramolecular Charge Transfer Interactions

Solventless Polymerization at the Gas–Solid Interface to Form Polymeric Thin Films

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